We report a case of a woman who underwent a curative resection of an upper jaw tumor histologically verified as eosinophilic granuloma. To exclude possible multiorgan involvement, PET/CT imaging was performed and revealed a metabolically active, partially calcified lesion located on the chest wall surface and clinically corresponding to a gradually developing, round, subcutaneous infiltrate with erythematous overlying skin. After complete extirpation, the pathological finding was consistent with pilomatrixoma surprisingly, thus dismissing the suspected diagnosis of multi-system Langerhans cell histiocytosis.